Marx generator circuits are widely used in high power applications in the scientific, industrial, and defense industries. Marx generators involve the charging of capacitors in parallel and the discharging of them in series. The objective of the generator circuit is to provide large output voltages and currents with fast rise times and minimum pulse jitter. For example, a Marx generator circuit may generate high voltage output pulses having a magnitude between 100 kV and 1 MV.
With reference to FIG. 1, a typical two stage Marx generator circuit 102 includes first and second capacitors 110,112. A first resistor 104 couples the circuit input to the first capacitor 110 and limits the charging current. Second and third resistors 106,108 couple the first and second capacitors 110,112 and isolate the capacitors 110,112 when the capacitors 110,112 are in series. A first switch 114 is used to alternatively connect the capacitors 110,112 in series and parallel. A second switch 116 couples the circuit to the output. To charge the circuit 102, the first and second switches 114,116 are open and the capacitors 110,112 are in parallel. To discharge the capacitors 110,112, the first switch 114 is closed placing the capacitors 110,112 in series. The second switch 116 is closed to deliver the output pulse. Typically, such circuits are composed of large individual components.
The typical Marx generator circuit described above has several physical and electrical constraints which limit its effectiveness in providing the desired large output voltages and currents and fast rise times.
First, the physical wiring coupling the separate components introduces power losses into the circuit. More importantly, the physical couplings add inductance to the circuit which acts towards slowing voltage and current rise times.
Second, the current limiting and isolating resistors 104,106,108 introduce power losses to the circuit.
Third as a result of the large voltages, the first and second capacitors (110,112) are typically large foil wound type capacitors. This type of capacitors has an inherent large inductance and limited current discharge capability due to the thinness of the conduction foils.
And fourth, also as result of the high operating voltages, the individual components tend to be quite large. In addition, because of the high voltage gradients, packaging results in large heavy assemblies.
The present invention is directed to overcoming one or more of the problems, as set forth above.